The present invention relates generally to temperature control in a refrigeration device. More particularly, the present invention relates to a back-up temperature control mechanism that allows a refrigerator or incubator to remain within a preset temperature range should the primary temperature control mechanism fail.
Electronic control packages have been developed for providing precise temperature control in refrigeration equipment including, e.g., ultra low freezers, incubators, and walk-in freezers. In refrigeration equipment, particularly in laboratory refrigeration equipment, the desire is to accurately maintain the temperature within the chamber below a desired set point. The selected set point would ordinarily be selected as the temperature necessary to preserve test samples from degradation. In refrigeration equipment, cooling is performed by absorbing heat within an enclosed chamber into a cooled refrigerant gas and transferring that heat into ambient air outside of the refrigeration device.
Similarly, incubators also exchange heat within a chamber to outside ambient air utilizing the same methods. Unlike refrigeration equipment, which operates to keep the chamber below a set point temperature, incubators must maintain the temperatures between lower and upper set point temperatures. While refrigeration equipment is typically used to preserve items placed in the chamber, incubators are used to conduct experiments in controlled temperature environments.
Thus, while refrigeration equipment only requires apparatus for cooling the inner chamber relative to ambient air temperature, an incubator must be able to both cool and heat the chamber to remain within the desired temperature range. In order to maintain highly precise temperature control in the foregoing devices, microprocessor control devices have been employed and are now standard on laboratory equipment.
While an electronic component on these controllers only fails occasionally, the damage an end-user of the refrigerator can suffer from such failure can be quite severe because products stored or being tested in the refrigeration equipment can be damaged or the tests compromised. Thus, the effects can be devastating when an electronic component fails, subjecting the stored products to unintended temperature conditions.
There is therefore a need for a temperature control mechanism which allows for backup control when a primary controller fails. More particularly, there is a need for a mechanism for refrigeration equipment to cycle within an acceptable temperature range automatically on failure of the primary temperature control thereby reducing the chances of property loss if the primary controller fails.
The foregoing needs are met, to a great extent, by the present invention where, in one aspect, a temperature control device is provided having a temperature sensor which senses temperature at a specified location within the refrigeration apparatus. The temperature control device has a first flow valve that is operable to selectively increase or decrease the flow of refrigerant in response to the temperature sensed by the sensor. In addition, the device has a second flow valve that is operable to selectively increase or decrease hot gas flow in response to the temperature sensed by the sensor. The temperature control device also contains a controller which controls the above mentioned valves in response to the temperature sensed by the temperature sensor.
In accordance with another aspect of the invention, the device includes a means for sensing a temperature at certain location of an incubation system. The device has a means for increasing or decreasing refrigerant flow in a first flow path in response to the temperature sensed by the sensing means. In addition, the device provides a means for increasing or decreasing hot gas flow in a second flow path in response to the temperature sensed by the sensing means. The device also provides a means for controlling the valves in response to the temperature in response to the temperature sensed by the sensing means.
In accordance with yet another aspect of the present invention, a method for providing back-up temperature control is provided by first maintaining the temperature inside a chamber within a selected range utilizing a first controller. Second, back-up temperature control is provided by sensing the temperature inside a chamber by utilizing a second temperature controller. Third, back-up temperature control is provided by measuring the the time duration after the compressor cycles on and a first valve is open. Fourth, back-up temperature control is provided by turning the first valve off after a predetermined time has passed and turning a second valve on. And finally, back-up temperature control is provided by cycling the compressor off when the temperature in the chamber is outside the selected range of the first controller and reaches a minimum temperature set point of the second temperature controller.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.